The present invention pertains to a method and apparatus for depositing metal alloy films. More particularly the present invention pertains to a method and apparatus for electroplating alloy metal films.
For a variety of technical applications it is desirable to be able to deposit multilayer films. For example, in semiconductor manufacturing applications a first layer of a multilayer film can be chosen based on its compatibility with the substrate (e.g., based on it""s ability to adhere well to the substrate). A second layer, which provides further desired properties for the multilayer film such as high electrical conductivity or high corrosion resistance, is then deposited on the first layer.
A standard method for electroplating a multilayer film onto a substrate, is to use separate electroplating baths to deposit each layer of the multilayer film. During a transfer from one electroplating bath to another, an exposed surface of the multilayer film can become passivated by the formation of a native oxide of an exposed metal. The native oxide can hinder further electroplating, and can interfere with interfacial bonding between successive layers of the multilayer film. It may be possible to remove the native oxide, doing so requires additional chemical processing, which may also require the use of environmentally hazardous chemicals. Further, moving a substrate through an liquid/air interface is a major source of particulate contamination of substrates.
In response to such contamination problems, and the environmental problems of wet processing, the semiconductor industry migrated toward all xe2x80x9cdryxe2x80x9d processing during the 1980""s. For example chemical vapor deposition (CVD), and sputtering are now typically used to deposit films in the semiconductor industry.
However, dry processing such as CVD or sputtering entails a high cost for purchasing and operating complex equipment which can include costly vacuum systems, and high frequency power supplies, and the use of hazardous gases.
Certain dry processing systems which avoid exposing substrates to the air have been proposed. However, these systems require costly evacuated or nitrogen purged containers and processing equipment fitted with specially designed ports for receiving the containers.
It would be desirable to be able to use the relatively inexpensive process of electroplating to deposit multilayer films.
Further, it would be desirable to be able use electroplating without incurring the problem of native oxide formation when transferring a substrate through the air between two electroplating baths.
Further, it would be desirable to be able to use electroplating for depositing multilayer films while reducing the potential for contamination of the substrate.
According to a preferred embodiment of the present invention an electroplating apparatus includes an electroplating bath container, a first electrolyte contained in the container, a second electrolyte contained in the container; and a barrier substance contained in the container.
A method for electroplating multilayer films is also provided.